linux-kernel - [PATCH 4/9] KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry

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Message-Id: <20201231002702.2223707-5-seanjc@google.com>
Date:   Wed, 30 Dec 2020 16:26:57 -0800
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>,
        "H. Peter Anvin" <hpa@...or.com>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org,
        "David P . Reed" <dpreed@...pplum.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Uros Bizjak <ubizjak@...il.com>
Subject: [PATCH 4/9] KVM/nVMX: Use __vmx_vcpu_run in nested_vmx_check_vmentry_hw

From: Uros Bizjak <ubizjak@...il.com>

Replace inline assembly in nested_vmx_check_vmentry_hw
with a call to __vmx_vcpu_run.  The function is not
performance critical, so (double) GPR save/restore
in __vmx_vcpu_run can be tolerated, as far as performance
effects are concerned.

Cc: Paolo Bonzini <pbonzini@...hat.com>
Cc: Sean Christopherson <seanjc@...gle.com>
Reviewed-and-tested-by: Sean Christopherson <seanjc@...gle.com>
Signed-off-by: Uros Bizjak <ubizjak@...il.com>
[sean: dropped versioning info from changelog]
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/nested.c  | 32 +++-----------------------------
 arch/x86/kvm/vmx/vmenter.S |  2 +-
 arch/x86/kvm/vmx/vmx.c     |  2 --
 arch/x86/kvm/vmx/vmx.h     |  1 +
 4 files changed, 5 insertions(+), 32 deletions(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index e2f26564a12d..5bbb4d667370 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -12,6 +12,7 @@
 #include "nested.h"
 #include "pmu.h"
 #include "trace.h"
+#include "vmx.h"
 #include "x86.h"
 
 static bool __read_mostly enable_shadow_vmcs = 1;
@@ -3057,35 +3058,8 @@ static int nested_vmx_check_vmentry_hw(struct kvm_vcpu *vcpu)
 		vmx->loaded_vmcs->host_state.cr4 = cr4;
 	}
 
-	asm(
-		"sub $%c[wordsize], %%" _ASM_SP "\n\t" /* temporarily adjust RSP for CALL */
-		"cmp %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"je 1f \n\t"
-		__ex("vmwrite %%" _ASM_SP ", %[HOST_RSP]") "\n\t"
-		"mov %%" _ASM_SP ", %c[host_state_rsp](%[loaded_vmcs]) \n\t"
-		"1: \n\t"
-		"add $%c[wordsize], %%" _ASM_SP "\n\t" /* un-adjust RSP */
-
-		/* Check if vmlaunch or vmresume is needed */
-		"cmpb $0, %c[launched](%[loaded_vmcs])\n\t"
-
-		/*
-		 * VMLAUNCH and VMRESUME clear RFLAGS.{CF,ZF} on VM-Exit, set
-		 * RFLAGS.CF on VM-Fail Invalid and set RFLAGS.ZF on VM-Fail
-		 * Valid.  vmx_vmenter() directly "returns" RFLAGS, and so the
-		 * results of VM-Enter is captured via CC_{SET,OUT} to vm_fail.
-		 */
-		"call vmx_vmenter\n\t"
-
-		CC_SET(be)
-	      : ASM_CALL_CONSTRAINT, CC_OUT(be) (vm_fail)
-	      :	[HOST_RSP]"r"((unsigned long)HOST_RSP),
-		[loaded_vmcs]"r"(vmx->loaded_vmcs),
-		[launched]"i"(offsetof(struct loaded_vmcs, launched)),
-		[host_state_rsp]"i"(offsetof(struct loaded_vmcs, host_state.rsp)),
-		[wordsize]"i"(sizeof(ulong))
-	      : "memory"
-	);
+	vm_fail = __vmx_vcpu_run(vmx, (unsigned long *)&vcpu->arch.regs,
+				 vmx->loaded_vmcs->launched);
 
 	if (vmx->msr_autoload.host.nr)
 		vmcs_write32(VM_EXIT_MSR_LOAD_COUNT, vmx->msr_autoload.host.nr);
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S
index e85aa5faa22d..3a6461694fc2 100644
--- a/arch/x86/kvm/vmx/vmenter.S
+++ b/arch/x86/kvm/vmx/vmenter.S
@@ -44,7 +44,7 @@
  * they VM-Fail, whereas a successful VM-Enter + VM-Exit will jump
  * to vmx_vmexit.
  */
-SYM_FUNC_START(vmx_vmenter)
+SYM_FUNC_START_LOCAL(vmx_vmenter)
 	/* EFLAGS.ZF is set if VMCS.LAUNCHED == 0 */
 	je 2f
 
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index 75c9c6a0a3a4..65b5f02b199f 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -6577,8 +6577,6 @@ static fastpath_t vmx_exit_handlers_fastpath(struct kvm_vcpu *vcpu)
 	}
 }
 
-bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
-
 static noinstr void vmx_vcpu_enter_exit(struct kvm_vcpu *vcpu,
 					struct vcpu_vmx *vmx)
 {
diff --git a/arch/x86/kvm/vmx/vmx.h b/arch/x86/kvm/vmx/vmx.h
index 9d3a557949ac..03fc90569ae1 100644
--- a/arch/x86/kvm/vmx/vmx.h
+++ b/arch/x86/kvm/vmx/vmx.h
@@ -339,6 +339,7 @@ void vmx_set_virtual_apic_mode(struct kvm_vcpu *vcpu);
 struct vmx_uret_msr *vmx_find_uret_msr(struct vcpu_vmx *vmx, u32 msr);
 void pt_update_intercept_for_msr(struct kvm_vcpu *vcpu);
 void vmx_update_host_rsp(struct vcpu_vmx *vmx, unsigned long host_rsp);
+bool __vmx_vcpu_run(struct vcpu_vmx *vmx, unsigned long *regs, bool launched);
 int vmx_find_loadstore_msr_slot(struct vmx_msrs *m, u32 msr);
 void vmx_ept_load_pdptrs(struct kvm_vcpu *vcpu);
 
-- 
2.29.2.729.g45daf8777d-goog